OPR-K339-KR-16 Offshore SW Pass Gulf of Mexico eTrac Inc. H12943 3 8 NM West of SW Pass Louisiana United States 40000 2016 David Neff, ACSM C.H. Basic Hydrographic Survey 2016-06-29 2016-08-03 2016-10-02 Multibeam Echo Sounder Multibeam Echo Sounder Backscatter meters Universal Transverse Mercator (UTM) UTC Atlantic Hydrographic Branch All times are UTC. The purpose of this survey is to update existing NOS nautical charts. H12943 will cover approximately 53 square nautical miles of survey area 8 NM SW Pass as designated in NOAA Hydrographic Survey Priorities, 2012 edition. SUBCONSULTANT: Geodynamics LLC, 310A Greenfield Dr., Newport, NC 98570 SUBCONSULTANT: Theory Marine, 777 Viewcrest DR., Ventura, CA 93003 Projections: UTM 16N, WGS 84 Contractor eTrac Inc. conducted hydrographic survey operations in the vicinity of SW Pass, LA. H12943 covers approximately 53 square nautical miles of survey area. 831 lineal nautical miles were aquired during the survey. H12943 is generally rectangular in geometry, and is approximately 13 nautical miles wide (E-W) by 4 nautical miles long (N-S). Survey was conducted within these limits between August 3, 2016 (DN216) and October 2, 2016 (DN276). 29.026519 89.700597 28.861983 89.455997 Survey Limits (black line) SUPPORTFILES/H12943_SHEETLIMITS.JPG All data were acquired in accordance with the requirements in the Project Instructions and specifications set forth in the Hydrographic Survey Specifications and Deliverables 2016 Edition (HSSD 2016). The purpose of this survey is to update existing NOS nautical charts. H12943 covers approximately 53 square nautical miles of survey area 8 NM West of SW Pass as designated in NOAA Hydrographic Survey Priorities, 2012 edition. The entire survey is adequate to supersede previous data. Survey H12943 is accurate to IHO Order 1a as required per the HSSD 2016. Survey Coverage was in accordance with the requirements in the Project Instructions and HSSD 2016. Depths in H12943 range from 8 to 65 meters. H12943 was surveyed to Complete Coverage MBES with backscatter standards set forth in the HSSD 2016. Survey Coverage SUPPORTFILES/H12943_SURVEY_COVERAGE.JPG Theory 0 413 0 0 0 0 0 34 0 Benthos 0 323 0 0 0 0 0 9 0 Taku 0 209 0 0 0 0 0 0 0 0 945 0 0 0 0 0 45 0 4.55 10 0 0 0 0 53 2016-08-03 2016-08-07 2016-08-09 2016-08-14 2016-08-15 2016-08-16 2016-08-17 2016-08-26 2016-08-27 2016-08-29 2016-08-30 2016-09-03 2016-09-14 2016-09-15 2016-09-16 2016-09-19 2016-09-20 2016-09-21 2016-09-22 2016-09-25 2016-10-02 Refer to the Data Acquisition and Processing Report (DAPR) for a complete description of data acquisition and processing systems, survey vessels, quality control procedures and data processing methods. Additional information to supplement sounding and survey data are discussed in the following sections. M/V Theory 11 0.75 R/V Benthos 10 0.6 R/V Taku 10 0.6 The R/V Benthos is a 10 meter aluminum catamaran equipped with a custom over-the-side (port) multibeam hydraulic pole mount, as well as a downrigger for SVP deployment. The R/V Taku is a 10 meter aluminum catamaran equipped with two Universal Sonar Mount (USM) over-the-side (port or port and starboard) multibeam mount(s), as well as an electric pot puller for SVP deployment. The M/V Theory is a 11 meter aluminum catamaran equipped with an Universal Sonar Mount (USM) over-the-stern multibean mount, as well as an A-frame for SVP deployment. R2Sonic 2024 MBES Applanix POSMV 320 V5 Positioning and Attitude System AML Base.X Sound Speed System AML Base.X2 Sound Speed System Trimble SPS461 Positioning System Trimble DSM232 Positioning System Note: The major systems listed above were used on each vessel. R/V Benthos utilized an AML Base.X for the sound speed system and a Trimble SPS461 for the positioning system. R/V Taku utilized an AML Base.X2 for the sound speed system and a Trimble DSM232 for the positioning system. M/V Theory utilized an AML Base.X2 for the sound speed system and a Trimble DSM232 for the positioning system. A comparison of crossline mileage to mainscheme mileage yields a crossline percentage of 4.55%, and is noted to be above the required 4%. A beam-by-beam statistical analysis was performed using the Line QC reporting tool in Caris HIPS and SIPS 9.1. A 4 meter CUBE weighted BASE surface was created incorporating only the mainscheme lines and excluded crosslines. The Line QC reporting tool was used to perform the beam-by-beam comparison of the crossline data to the mainscheme surface. Comparisons showed excellent agreement, well above 95% of the allowable TVU. Note: This surface was created for QC only and is not submitted as a surface deliverable. The beam-to-beam crossline comparison report generated through the Caris QC Reporting tool is included in Separate II. Below is a graph of crossline comparison statistics showing IHO Order 1a compliance per beam. H12943 Crossline Comparison (4m) SUPPORTFILES/H12943_CROSSLINECOMPARISON_4M.JPG M/V Theory 4 0 2 R/V Benthos 4 0 2 R/V Taku 4 0 2 Note: The survey specific tide TPU values for measured and zoning tides are computed internally within TCARI. Standard deviation and uncertainty child layers of BASE surfaces were utilized during data processing to search for features, water column noise, and systematic errors. A custom child layer was created within the BASE surface utilizing the Deep and Shoal layers in the following configuration: Custom Layer = (Deep - Shoal)^2 By viewing this custom layer, seafloor features, water column noise, and systematic errors are graphically exaggerated and can easily be identified for further examination. A TVU QC layer was created within the BASE surface utilizing the Uncertainty and Depth child layers in the following configuration: -Uncertainty/((0.5^2 +((Depth*0.013)^2))^0.5) By viewing the TVU QC layer, nodes that exceed the IHO Order 1a uncertainty standards can be identified and further analyzed. Standard deviation and uncertainty were quantified using the QC Reporting tool within Caris HIPS and SIPS 9.1. The option "Greater of the two" was selected in the reporting tool in order to generate statistics quantifying the maximum error occurring within the data. IHO Order 1a uncertainty specification was met by 100% of the nodes. Each BASE surface's uncertainty QC report generated through the Caris QC Reporting tool is included in Separate II. The Total Propogated Uncertainty (TPU) was evaluated using the TPUTrac program in the AmiTrac program, developed in-house by eTrac Inc. Each finalized BASE surface's nodes were exported to an ASCII CSV file where the fields were (Easting, Northing, Depth, Uncertainty, Density) for each node. The CSV file was then loaded into the TPUTrac program and the TPU statistics were computed. A file was also created in this process to locate any points that exceed the allowable TPU, which was imported into Caris HIPS and SIPS 9.1 and any identified points from TPUTrac were analyzed and evaluated. For H12943 the following percentages represent the results of the TPU testing: Complete Coverage MBES (Finalized 1m CUBE weighted BASE Surface) = 100% of nodes are within allowable TPU. Complete Coverage MBES (Finalized 2m CUBE weighted BASE Surface) = 99.9988% of nodes are within allowable TPU. Complete Coverage MBES (Finalized 4m CUBE weighted BASE Surface) = 99.9994% of nodes are within allowable TPU. H12943 Finalized 1m Complete Coverage MBES TPU Statistics SUPPORTFILES/H12943_1M_TPUTRAC_FINAL.JPG H12943 Finalized 2m Complete Coverage MBES TPU Statistics SUPPORTFILES/H12943_2M_TPUTRAC_FINAL.JPG H12943 Finalized 4m Complete Coverage MBES TPU Statistics SUPPORTFILES/H12943_4M_TPUTRAC_FINAL.JPG Depth differences between junctioning surveys were evaluated using the JunctionTrac program, developed in-house by eTrac Inc. For each junction, each BASE surface's nodes were exported to an ASCII CSV file where the fields were (Easting, Northing, Depth) for each node. A 4m difference surface between the junctioning datasets was also created and exported to an ASCII CSV file where the fields were (Easting, Northing, Diff) for each node. The three ASCII CSV files were then loaded into the JunctionTrac program and junction statistics were computed. A file was also created in this process to locate any nodes from the difference surface that exceed the allowable TVU, which was imported into Caris HIPS and SIPS 9.1 and any identified points from JunctionTrac were analyzed. Note: the difference surfaces were created for comparison efforts only and are not submitted as surface deliverables. H12944 40000 2016 eTrac Inc. S H12943 junctions with H12944 to the South. The junction comparison was performed using approximately 560m of overlapping data between H12943 and H12944. Depth differences were evaluated using the JunctionTrac program, developed in-house by eTrac Inc. Below is a histogram of junction comparison statistics showing the difference between the junctioning surfaces and allowable TVU. 99.8672% of nodes were within allowable TVU. H12943 and H12944 overlap a fish haven where multiple features are located. The extreme outliers in the below graph are noted to be caused by these features being represented slightly differently in the respective surfaces. Junction comparison statistics are also included in Separate II. H12943 - H12944 Junction Comparison SUPPORTFILES/H12943_H12944_JUNCTIONTRAC.JPG H12553 40000 2013 Oceans Surveys, Inc. SW H12943 junctions with H12553 to the Southwest. The junction comparison was performed using approximately 240m of overlapping data between H12943 and H12553. Depth differences were evaluated using the JunctionTrac program, developed in-house by eTrac Inc. Below is a histogram of junction comparison statistics showing the difference between the junctioning surfaces and allowable TVU. 99.8805% of nodes were within allowable TVU. Junction comparison statistics are also included in Separate II. H12943 - H12553 Junction Comparison SUPPORTFILES/H12943_H12553_JUNCTIONTRAC.JPG H12552 40000 2013 Oceans Surveys, Inc. NW H12943 junctions with H12552 to the Northwest. The junction comparison was performed using approximately 240m of overlapping data between H12943 and H12552. Depth differences were evaluated using the JunctionTrac program, developed in-house by eTrac Inc. Below is a histogram of junction comparison statistics showing the difference between the junctioning surfaces and allowable TVU. 99.9982% of nodes were within allowable TVU. Junction comparison statistics are also included in Separate II. H12943 - H12552 Junction Comparison SUPPORTFILES/H12943_H12552_JUNCTIONTRAC.JPG H12716 40000 2014 Fugro Pelagos, Inc. N H12943 junctions with H12716 to the North. The junction comparison was performed using approximately 200m of overlapping data between H12943 and H12716. Depth differences were evaluated using the JunctionTrac program, developed in-house by eTrac Inc. Below is a histogram of junction comparison statistics showing the difference between the junctioning surfaces and allowable TVU. 99.9725% of nodes were within allowable TVU. Junction comparison statistics are also included in Separate II. H12943 - H12716 Junction Comparison SUPPORTFILES/H12943_H12716_JUNCTIONTRAC.JPG H12635 40000 2014 C & C Technologies, Inc. N H12943 junctions with H12635 to the North. The junction comparison was performed using approximately 210m of overlapping data between H12943 and H12635. Depth differences were evaluated using the JunctionTrac program, developed in-house by eTrac Inc. Below is a histogram of junction comparison statistics showing the difference between the junctioning surfaces and allowable TVU. 100% of nodes were within allowable TVU. Junction comparison statistics are also included in Separate II. H12943 - H12635 Junction Comparison SUPPORTFILES/H12943_H12635_JUNCTIONTRAC.JPG H12634 40000 2014 C & C Technologies, Inc. E H12943 junctions with H12634 to the East. The junction comparison was performed using approximately 240m of overlapping data between H12943 and H12634. Depth differences were evaluated using the JunctionTrac program, developed in-house by eTrac Inc. Below is a histogram of junction comparison statistics showing the difference between the junctioning surfaces and allowable TVU. 92.1024% of nodes were within allowable TVU. The junction of H12943 and H12634 is located near the mouth of SW Pass. The lower percentage is likely caused by a shoaling trend observed in the eastern region of H12943, near the mouth of SW pass. This observation is further evaluated in the Chart Comparison with RNC 11361 in section D.1.1 of this report. Junction comparison statistics are also included in Separate II. H12943 - H12634 Junction Comparison SUPPORTFILES/H12943_H12634_JUNCTIONTRAC.JPG Sonar system quality control checks were conducted as detailed in the quality control section of the DAPR. None Exist There were no conditions or deficiencies that affected equipment operational effectiveness. None Exist There were no other factors that affected corrections to soundings. SVP casts were generally taken every 2 hours. Ocassionally casts would exceed a 2 hour frequency, however would never exceed a 4 hour frequency. Casts were applied in QPS QINSy acquisition software at the time of the cast. Surface SVP measured at 1Hz was compared to surface speed from the current profile in realtime. If the surface velocity comparison was in excess of 2m/s at any time during survey operations, a new cast was taken. SVP surface velocities were compared in realtime and profile to profile for each cast on the vessel. Additionally, profiles were compared day-to-day in the field office using the SVPTrac program, developed in-house by eTrac Inc., to better understand trends for efficient acquisition planning. Example of Daily SVP Data Plot (DN260) SUPPORTFILES/H1294_SVP_TA_DN260.JPG Example of Day to Day SVP Comparison (DN259 and DN260) SUPPORTFILES/H1294_SVP_BE259_260.JPG All equipment and survey methods were used as detailed in the DAPR. Data Density Evaluation In order to determine if the density of the data met the specified 5 soundings per node, data density was evaluated using the DensityTrac program in the AmiTrac program, developed in-house by eTrac Inc. Each finalized BASE surface's nodes were exported to an ASCII CSV file where the fields were (Easting, Northing, Depth, Uncertainty, Density) for each node. The CSV file was then loaded into the DensityTrac program and density statistics were computed. For H12943 the following percentages represent the results of the density testing: Complete Coverage MBES (Finalized 1m CUBE weighted BASE Surface ) = 99.8236% of nodes are composed from at least 5 soundings. Complete Coverage MBES (Finalized 2m CUBE weighted BASE Surface ) = 99.4315% of nodes are composed from at least 5 soundings. Complete Coverage MBES (Finalized 4m CUBE weighted BASE Surface ) = 99.8937% of nodes are composed from at least 5 soundings. H12943 Finalized 1m Complete Coverage MBES Density Distribution Statistics SUPPORTFILES/H12943_DENSITYHISTOGRAM_1M_FINAL.JPG H12943 Finalized 2m Complete Coverage MBES Density Distribution Statistics SUPPORTFILES/H12943_DENSITYHISTOGRAM_2M_FINAL.JPG H12943 Finalized 4m Complete Coverage MBES Density Distribution Statistics SUPPORTFILES/H12943_DENSITYHISTOGRAM_4M_FINAL.JPG All data reduction procedures conform to those detailed in the DAPR. All sounding systems were calibrated as detailed in the DAPR. Backscatter data were collected throughout the survey and are retained in the raw XTF files. Every effort was made in the field to collect quality backscatter data while maintaining the primary mandate of high quality bathymetric data. While no processing or analysis of backscatter was required, eTrac Inc. engaged in a minimal effort to verify coverage and general quality of the backscatter data collected. Raw backscatter data were viewed in Caris HIPS and SIPS 9.1 to ensure collection criteria had been met. Shown below is an example of the unprocessed backscatter mosaic from H12943 DN227. Raw Backscatter from R/V Benthos (DN227) SUPPORTFILES/H12943_BACKSCATTER_BE_DN227.JPG NOAA Profile V_5_4 H12943_MB_1m_MLLW CUBE 1 8.78 56.13 NOAA_1m Complete MBES H12943_MB_2m_MLLW CUBE 2 8.79 65.32 NOAA_2m Complete MBES H12943_MB_4m_MLLW CUBE 4 8.79 64.85 NOAA_4m Complete MBES H12943_MB_1m_MLLW_Final CUBE 1 8.78 20 NOAA_1m Complete MBES H12943_MB_2m_MLLW_Final CUBE 2 18 40 NOAA_2m Complete MBES H12943_MB_4m_MLLW_Final CUBE 4 36 64.85 NOAA_4m Complete MBES In areas shoaler than 18 meters, a 1m surface is provided meeting complete coverage MBES with backscatter specifications. In areas ranging from 18 meters to 40 meters, a 2m surface is provided meeting complete coverage MBES with backscatter specifications. This surface covers the northwestern corner and eastern portion of H12943 as well as 532 nodes of features in the 3 fish havens in H12943 which include 5 designated sounding nodes that are shoaler than the 4m threshold. In areas deeper than 36 meters, a 4m surface is provided meeting complete coverage MBES with backscatter specifications. Parent surfaces of the 1m, 2m, and 4m surfaces are provided. The 2m and 4m parent surfaces both cover the entire survey area of H12943. The 1m parent surface covers the eastern end of the survey area where depths become shoaler. H12943 Delivered BASE Surface Coverage Graphic SUPPORTFILES/H12943_SURFACES_COVERAGE.JPG Water Column Data Water column data was collected during investigations and over features in H12943. Water column data was used during the analysis of a significant feature found in H12943. This feature is detailed in Section D.2.8 of this report. Mean Lower Low Water TCARI 8760922.tid Final Approved 8761724.tid Final Approved 8762075.tid Final Approved K339KR2016Final.tc Final 2016-10-03 2016-10-25 In order to reference soundings to MLLW, the Tidal Constituent And Residual Interpolator (TCARI) method was applied to the HDCS data via the TCARI program. TCARI compiled information from SW Pass, LA (8760922), Grand Isle, LA (8761724), and Port Fourchon, LA (8762075). Note: Any vertical control method deviations from the Project Instructions are addressed in the DAPR. World Geodetic System of 1984 (WGS84) UTM Zone 16N English Turn, 293kHz, ID: 814 During main acquisition R/V Benthos, R/V Taku, and M/V Theory received GNSS satellite corrections over the POS MV G2 carrier signal from the Marinestar Global Correction System maintained by Fugro. The Marinestar system is a global realtime GNSS broadcast system that delivers corrections from an array of base stations around the world via geo-stationary satellites. Corrections were monitored realtime during data acquisition to ensure no dropouts occurred and the POSMV maintained differential accuracies throughout the survey. No dropouts were witnessed during data collection. Position data were analyzed in the office during post-processing. The attitude editor within Caris HIPS and SIPS 9.1 was utilized to identify any position data that may be insufficient for final delivery. DGPS stations were only to be used as a backup horizontal correction source. G2 Marinestar correctors were used as the primary correction source. DGPS was never utilized, as G2 corrections were available throughout all survey operations. A chart comparison was conducted for H12943 using Caris HIPS and SIPS 9.1. Contours, as well as soundings, were compared against the largest scale RNC 11358 and ENC US4LA32M to accomplish the chart comparison. RNC 11358 and ENC US4LA32M do not cover the eastern half of H12943, and therefor RNC 11361_1 and ENC US4LA30M were included to complete the chart comparison. The methods and results of the comparison are detailed below. Contour Comparison Method: Using the 4 meter CUBE weighted BASE surface, the 60 foot, 120 foot and 180 foot contours were generated and displayed against the charted contour. Additionally, the 4 meter CUBE weighted BASE surface was viewed by a custom color band range based on the contour intervals (60ft, 120ft, 180ft, 240ft, 300ft, 400ft). The results of the comparison are described below. Sounding Comparison Method: Using the same 4 meter CUBE weighted BASE surface used for the contour comparison, spot soundings were generated in Caris HIPS and SIPS 9.1 for H12943. Soundings were displayed against the charted soundings and a visual comparison was made. The results are described below. 11358 0 80000 58 2014-05 2016-05-18 2016-05-22 Contour Comparison Results: The 180ft contour has neither progressed or receeded from the western portion of the charted contour. The 180ft contour has progressed seaward, approximately 400 feet from the central portion of the charted contour. The 180ft contour has progressed seaward, approximately 1,500 feet from the eastern portion of the charted contour. Sounding Comparison Results: In the western region of H12943, with the exception to the differences identified through the contour comparison, in general, the soundings are in excellent agreement, with no major discrepancies. Soundings are generally within 1 foot of each other. Occasionally soundings differ by 2 to 3 feet, however depth differences appear to be minimal. Depth differences are not biased in any particular direction to support a systematic error. In the central region of H12943, with the exception to the differences identified through the contour comparison, in general, the soundings are in great agreement, with no major discrepancies. Soundings are generally within 3 feet of each other. Occasionally soundings differ by 5 to 8 feet, hower greater depth differences appear to be minimal. Depth differences are not biased in any particular direction to support a systematic error. 11361 1 80000 78 2014-07 2016-05-17 2016-05-21 Contour Comparison Results: A general shoaling trend is observed in the eastern region of H12943. The area where shoaling is observed is located near the mouth of SW Pass. Sediment moving out of the delta is the probable cause of this event. The 60ft contour has progressed seaward, on average, approximately 3,500 feet from the charted contour. The 120ft contour has progressed seaward, on average, approximately 4,000 feet from the charted contour. The 180ft contour has progressed seaward, on average, approximately 2,000 feet from the charted contour. Sounding Comparison Results: With support from the differences identified through the contour comparison, in general, the soundings in H12943 are shoaler than the charted soundings. The discrepencies vary an estimated 1-40 feet shoaler from the charted soundings. Although soundings of H12943 are shoaler than the charted soundings, depth differences do not support a systematic error. H12943 Contour Comparison (Overview) SUPPORTFILES/H12943_CONTOURS_OVERVIEW.JPG H12943 Contour Comparison (60ft and 120ft Contour) SUPPORTFILES/H12943_60FT_120FT_CONTOUR.JPG H12943 Contour Comparison (180ft Contour) SUPPORTFILES/H12943_180FT_CONTOUR.JPG Sounding Comparison (RNC 11358) SUPPORTFILES/H12943_RNC11358_SOUNDINGCOMPARISON.JPG Sounding Comparison (RNC 11361) SUPPORTFILES/H12943_RNC11361_SOUNDINGCOMPARISON.JPG US4LA32M 80000 32 2014-10-01 2016-04-26 false The results of the chart comparison with ENC US4LA32M match those of the chart comparison with RNC 11358. US4LA30M 80000 28 2014-07-23 2016-04-06 false The results of the chart comparison with ENC US4LA32M match those of the chart comparison with RNC 11358. No AWOIS Items were assigned for this survey. No Maritime Boundary Points were assigned for this survey. There were 13 charted features assigned to H12943. Each assigned feature is retained in the Final Feature File (FFF). Each feature in the FFF has been given a unique identifier in the "userid" field of the .000 S-57 file (format H12943_XXX). Refer to the FFF for determinations and recommendations of each feature. There was 1 unassigned, charted feature in H12943 that was added to the FFF. Each feature in the FFF has been given a unique identifier in the "userid" field of the .000 S-57 file (format H12943_XXX). Refer to the FFF for determinations and recommendations of each feature. 2 new features were found in H12943 and were added to the Final Feature File (FFF). The features were each given a unique identifier in the "userid" field of the .000 S-57 file (format H12943_XXX). Refer to the FFF for determinations and recommendations of each feature. There were 49 uncharted features assigned to H12943. Each assigned feature is retained in the FFF. Each feature in the FFF has been given a unique identifier in the "userid" field of the .000 S-57 file (format H12943_XXX). Refer to the FFF for determinations and recommendations of each feature. Note: All 49 assigned, uncharted features are listed as BSEE Wellheads. BSEE Wellhead Example (represented in the surface) SUPPORTFILES/H12943_BSEE_WELLHEAD_REPRESENTED_IN_SURFACE.JPG BSEE Wellhead Example (location of unassigned charted platform) SUPPORTFILES/H12943_BSEE_WELLHEAD_IN_LOCATION_OF_PLATFORM.JPG 1 H12943_DtoN_01 2016-09-08 1 DTON was found in this survey, and was added to the Final Feature File (FFF). Each feature in the FFF has been given a unique identifier in the "userid" field of the .000 S-57 file (format H12943_XXX). Refer to the FFF for determinations and recommendations of each feature. Note: This DTON was included in the number of new, uncharted features with section D.1.6. No shoals or potentially hazardous features exist for this survey. No channels exist for this survey. There are no designated anchorages, precautionary areas, safety fairways, traffic separation schemes, pilot boarding areas, or channels and range lines within the survey limits. 10 bottom samples were obtained in accordance with sections 7.2 and 7.2.2 of the HSSD 2016 in areas designated by the feature object class springs (SPRING) in the Project Reference File (PRF). A brief description of the results is listed below. H12943_C001: soft, grey, mud with sticky, black, clay H12943_C002: soft, black, clay H12943_C003: fine, grey, mud, with soft, black, clay H12943_C004: soft, grey, mud with sticky, black, clay H12943_C005: soft, black, clay H12943_C006: soft, grey, mud with sticky, black, clay H12943_C007: soft, grey, mud H12943_C008: soft, grey, mud H12943_C009: soft, grey, mud H12943_C010: soft, brown, mud Detailed information and images of the bottom samples listed above are located in the Final Feature File (FFF). Each bottom sample has been given a unique identifier in the "userid" field of the .000 S-57 file (format H12943_CXXX). No shoreline exists for this survey. No prior survey comparisons exist for this survey. No Aids to Navigation (ATONs) exist for this survey. No overhead features exist for this survey. No submarine features exist for this survey. No ferry routes or terminals exist for this survey. There were no platforms specifically assigned for this survey. 1 charted, unassigned platform was not observed, and was added to the Final Feature File (FFF). Each feature in the FFF has been given a unique identifier in the "userid" field of the .000 S-57 file (format H12943_XXX). Refer to the FFF for determinations and recommendations of each feature. Note: This feature was included in the number of charted, unassigned features within section D.1.5. A significant feature was found in H12943. The feature has the form and morphology typical of ascending gas or bubble plumes with no detectable structure and was found while investigating assigned BSEE wellhead with unique ID: H12943_347 at LAT:28-56.92N LON:089-35.96W. This feature is approximately 5 meters from the provided location of the BSEE wellhead and approximately 30 meters from a charted wellhead (unique ID H12943_301). The soundings of this feature were disabled in Caris HIPS and SIPS 9.1 so they are not represented in the delivered grids. This feature was also detected and analyzed in water column data. Reference Email Correspondence in Appendix II of this report. Significant Feature SUPPORTFILES/H12943_SIGNIFICANT_FEATURE.PNG Significant Feature (Water Column Data) SUPPORTFILES/H12943_SIGNIFICANT_FEATURE_WATERCOLUMN.PNG No present or planned construction or dredging exist within the survey limits. No new surveys or further investigations are recommended for this area. No new insets are recommended for this area. As Chief of Party, field operations for this hydrographic survey were conducted under my direct supervision, with frequent personal checks of progress and adequacy. I have reviewed the attached survey data and reports. All BASE surfaces, this Descriptive Report, and all accompanying records and data are approved. All records are forwarded for final review and processing to the Processing Branch. The survey data meets or exceeds requirements as set forth in the NOS Hydrographic Surveys and Specifications Deliverables Manual, Field Procedures Manual, Letter Instructions, and all HSD Technical Directives. These data are adequate to supersede charted data in their common areas. This survey is complete and no additional work is required with the exception of deficiencies noted in the Descriptive Report. David R. Neff, C.H. VP of Survey, eTrac Inc. 2016-12-05